Allison-
You need to do what feels right for your family regarding the birds and the bees. I'll share my story, and maybe others will also.
My son was 3.5 when his little sister was born. So quite naturally, he became interested in the birds and the bees when he was around three. He used to read my childbirth books and watch childbirth videos and a tv show which I think was called, "A Baby's Story". We bought him a couple children's books on the topic as well. So he was very well informed at an early age and too young to be embarrassed by any of it.
That little girl started growing up with all of these materials still hanging around the house. She asked lots of questions and though she wasn't reading much until about 2.5, she enjoyed looking at the photos and illustrations, and remembered everything she was told. We attended a party when this DD was 20 or 21 months old. There was a very pregnant woman there, and her only other child was six years old. She whispered to me that her son knew NOTHING and that they wanted to keep it that way. Later that evening, the boy asked about how the baby got into his Mom, and I had to steer my toddler out of the room, and distract her,lest she spill the beans! She was very articulate and would have given a short lecture on the topic! This is one of those incidents that stands out in my mind to illustrate how different my kids can be.
