supernatural inheritance

I'm looking for general thoughts on this topic- if the covenant wishes to breed horses which are unaffected by the gift, or breed sheep which have (form) monstrosity as a vis source. What are the options (including use of hedge wizards)? Can a Merinita ritual casting with target bloodline be passed on to new members of the bloodline, or only those alive when it is cast? Would fertility magic's benefits in terms of virtues be inheritable? If it is possible but not certain, for example with livestock, what percentage would it be passed down to?
I know modern understanding of genetics should not apply, I know very little about the Medieval paradigm on inheritance of traits.

No specific answers, but here are a few canon sources that may be helpful:

  • Broken Covenant of Calebais - Hrools
  • HoH:MC, Criamon section - The Avenue of a Thousand Beautiful Faces and the Station of Exalation
  • Against the Dark? Definitely mention of it somewhere... HoH:TL, Tremere section has it. - the Burning Acorn Vexillation are breeding partially fae horses
  • Ancient Magic - Fertility Magic

Edit: I remembered and fixed a couple above.

From what I recall of the medieval paradigm of inherited characteristics, it's pretty pragmatic - "large horses breed large horses, brown cows breed brown cows", etc. (which, generally speaking, they do.) While the modern science of genetics allows for a better understanding of what's going on, farmers and horse trainers were fully capable of breeding animals for specific characteristics. That's how we got varying domesticated breeds, after all. And up until the technology developed for artificial insemination (looks to be 1780, for dogs), you pretty much did it the natural way, anyway. As such, the end result in an Ars paradigm for genetics should probably be the same as in ours - or at least similar.

In terms of Hermetic sources, there's also the whole "let's grow vis from magical trees" in...Hermetic projects? I think that's a transferrable ability.

Breeding vis reliably, and having offspring preserve certain magical properties, was Hérisson's passion. You find his results and projects in LoH p.72ff Legacy.

Cheers

In doing a quick reading of the history of genetics, it looks like Mendellian genetics could be compatible with a medieval cosmology - simply because it was a statistical observation, rather than hypothesizing anything about genes. (pretty sure Medieval folks understood that sometimes traits could skip a generation. Mendellian genetics is really just formalizing that understanding into the concept of Dominant and Recessive traits.)

I recall reading where artificial insemination had been accomplished in the late medieval/early renaissance by someone, basically took a rag filled with the "male essence" and stuck it in the appropriate female organ (I forget if this was horses or cows), but actually understanding anything beyond the obvious basics is yes, modern. Breeding for certain traits is ne thing, breeding for extremely rare traits with limited resources something else...
I guess the first step is make sure your first generation has lots of offspring so you have more to work with...

Timothy Ferguson mentions in the games from folk-tales podcast in the labyrinth of lanes episode runs a proposed covenant in the Alps which has a Bjorner Magus who is a stallion and spends all his time at a stables that is famous for breeding horses that don't throw magi, if you wanted an idea for where you might find breeding stock for that project.

I'll add that the covenant of Lambaird in Hibernia already does this. They breed horses that are immune to the gift, dogs with Magic Sensitivity, and magic falcons.

If you're in a different Tribunal, I bet you could negotiate with them for some breeding stock. As long as there wasn't any competition within Hibernia.

Is there anything useful in the Menagerie section of HP?

Ha! We're doing this exact thing in our Rhine saga.

Our saga's breeding of magical horses uses a rough mechanic for easily tracking progress. Although it was not really been tested in practice.
I went for a concept where the dice weren't all-decisive, because I don't like it if an exploding stress die resolved everything the first year, nor a system where consistent bad luck makes for no progress ever.
The concept is rolling simple dice per breeding pair, where the male has the trait in question, and you aim for getting 0s. There is a scale where the number of 0s each year mean different things. it takes 4 0s to get a male offspring with the desired trait, but lower amounts of 0s (or even other results) means lesser progress, which statictically help in the following years. There are bonus dice for quality and quantity of food and stables, for magci aura, for magic spells or devices used to help, for skilled staff etc.

I'd call it more interesting in the way of inspiration rather than useful per se. It mentions some things about breeding animals with Might and passing along traits.

So if a Gruagrach gives a trait to say a horse using vis, can it breed true in the offspring?

This starts to get into the "what is a virtue/trait?" question - it's both a game mechanic as well as an in-game benefit. It is inheritable? As magic power does seem capable of being inherited (ie, Supernatural blood, and all that), I don't see why not. Without having the Gruganch rules in front of me - I would assume that it would breed true inasmuch as regular traits breed true. Dependent on how much of a Creo effect it is, and not a Muto.

Ie, I would argue that if someone used a Creo Corpus or Creo Mentem stat booster on a human being, that would be as likely to breed true as any other human trait. As from what I understand, Ars assumes that everyone is at their maximum potential, and as such can't improve their stats normally. Therefore, any actual improvement will, by definition, be changing the targets Essential Nature.

I would say no, because it's been added magically, rather than being part of the "Essential Nature" (TM). However, seeing as Gruagachan and Learned Magicians can target Bloodline a lot more easily than Merinita, you can certainly enchant a stallion and have all its offspring affected by the enchantment.

Can Gruagach actually use vis to make permanent changes? From what I can see, they can only use it to boost casting totals, study and tattoo enchantment, not for "ritual" effects. They can make semi-permanent effects using the Geas or Limit durations, but these aren't "natural" effects.

Ah - if that's the case, then I would agree that they don't breed true. Because, hey: why should I look up the rules when I can speculate needlessly and have others correct me?

okay, what if a magical entity with the grant virtue power permenantly grants the virtue? Is it hereditary? Can it be in some situations, and if so how would you decide when?

also I don't see anywhere that indicates that gruagrach can't cast permenant momentary spells the same as heretic magi.

I would assume that any permanent momentary spell would be a ritual.

Hedge Magic, p. 59 notes (with respect to gruagachan casting) that: "Their Formulaic spells are much more adaptable than those of Hermetic magi. But this adaptability comes at a price, and the gruagachan are neither able to conduct Ceremonial castings nor perform Rituals."

No rituals should mean no permanent momentary spells, as I understand things.

missed that- the gruagratch are in the background currently so I haven't gone over them with a fine toothed comb.

What about the Muspelli? Utisea augmented Shape-shifting, Summon Animals and Entrancement might allow for the breeding of magical animals (Some followers of Gullveig can have all three virtues.). They aren't likely to co-operate with Hermetics, but it could be possible.

Troya of Flambeau breeds magical horses to bear magus riders - Faith & Flame, p. 68.

There's also the lineage of magical cats, from... I forget where, but they've bred true, and I think it was through their own devices.