My mom had my youngest sibling when she was 41 1/2 years old. There is still some debate 40 years later whether she's normal or not!!
I can say that since she doesn't belong to this forum!! I was 15 1/2 when she was born and she's my only sister. It took about 25 years, but I can honestly say she's one of my best friends. Her kids are the same age group as my grandkids and she's closer in age to my kids than she is to me!!
