Came across this classic tale of an English deathbed curse:
http://books.google.com/books?id=ZEgEAAAAMBAJ&lpg=PA42&as_pt=MAGAZINES&pg=PA63#v=onepage&q&f=true
... reputedly from 1150. Told in LIFE magazine, May 12, 1947.
How would you implement this curse in game terms?
Don't have sourcebooks on me at the moment, but this looks like a Merinita style deal to me.
I always wondered why Bind Curses was a Verditius Mystery and not a Merinita one.
Without giving the spell level, I'd think that there are some ways to make this work in (mostly) Hermetic Magic:
Curse of the Tichford Dole PeCo(?) Special Merinita Mystery Spell
T: Bloodline, D: Bargain, Ritual R: Special, Mystery (Boundary). Repeats Annually. Relies on Mysteries of Spell Perpetuity (Living Bloodline) and Spell timing to function. As this spell really stretches the limits of Spell Perpetuity, you might use D: Bargain/Symbol instead, where a charm is made representing the Bargain between the Lady and the Lord, so that as long as the symbol endures, the bargain spell binds the family to its conditions.
The maga casts a ritual that, unless the conditions of a Bargain are met, the bloodline sufferes an affliction, in this case losing the ability to have male children, for as long as the Bargain remains unfulfilled. This might be substituted with other effects, or be random.
See Himnis Curses in the Verditius chapter of HoH: MC for more great ideas.
Extra option for in story flavour: This is one of a body of special mystery spells introduced to the House by a Folk Magic Tradition which joined the Order and the Cult in the early 11th century. They have never been fully integrated into Hermetic Magic, and remain a special corpus of spells that are part of the magic of House Merinita.
They require Story Magic, Symbolic Magic and Spell Perpetuity to perform. They may be cast as a normal ritual or using a Major Sacrifice, such as the sacrifice of a Talisman (with at least 4 seasons invested into it), Familiar or one's own life to empower the effect without need for the Ritual time.
I've always felt that SG's should encourage creative syntheses of Merinita Mystery effects because you can get super-cool effects like this.
I might make it that a supernatural creature witnessed it and used ritual power to bind the ones involved to the curse. Then it isn't hermetic at all. This is one of those mysterious faerie, demon, magic realm, divine curses that give the game such flavor.