I remember visiting my youngest niece just after she was born in 2002. I was holding her and cooing over her - because she really is a pretty child and still is - and my BIL, my sister's husband, poked my DH and said, "Now she'll be begging you for a baby."
My other BIL (my DH's brother) said the same thing to DH in 2004 when I admired and held his new son, who is the first grandchild in my DH's family. I could plainly see that BIL and his wife were going to get far more attention from DH's parents than DH and I would, since DH's mom had grandbaby-rabies for a long time before my nephew was born.
But guess what? DH and I didn't hop to have a baby in 2002 OR 2004.
Having a baby just because our siblings had them and received lots of attention from our parents as a result would have been a stupid reason!
I'd rather be ignored - as much as it hurts sometimes - than produce a child for them, since the child wouldn't actually be theirs - it would be ours to spend a lifetime raising.
And I get a little disgusted that I can't even admire and hold my own nieces and nephews or any other child without someone assuming that I can't wait to be a mother myself or that I'm going to beg my DH (who is just as CF as I am and has let his family know that) for a widdle baybee.