Snape's Age RE: Tonks's age: A possible solution

[Alec]

> I've wondered if the split in the family was actually a generation 
back
> so that Sirius's father and Bella's were first cousins. But Sirius's
> mother was also the sister of Bella's father. A first cousin marriage
> isn't so odd in this context whatever the fandom thinks. The reason I
> wonder this is because Mrs. Black refers to Grimmauld Place as "the
> house of my fathers", making me think she's no only related to her
> husband, but closely related. And secondly, I think she's portrayed 
as
> very like the older edition of Bellatrix, which would make sense if 
they
> were aunt and niece by blood.

Yes, she was clearly born a Black, and I'd wondered if the house in 
Grimmauld Place was "her's" by inheritance.

After all, Kreacher's primary loyalty was to "her", and not to her 
husband.