Lea my parents had my sister in 1977 then me in 1979 and 5 years later had my sister in 1984 and my brother in 1985, sort of like your XBIL. The reasoning for them was that in between me & my younger sister mum was pregnant with a little boy who died at aroun 19/20wks.

As for my cutoff - I always said I wanted to have a baby by the time I was 25, funnily enough Zander arrived 13 days before my 26th birhday We're planning on at least another 2 if not another 3 or 4 (ie somewhere between 3 & 5 total) and I'd like to be finished by the time I'm 35, so I have another 8 years to go.

Maggie IKWYM about having a cutoff when facing infertility. My cutoff I just mentioned is only theoretical as it's quite possible we won't be able to conceive anymore children. I just desperatley wanted one so anymore is just a bonus