explaining where babies come from to young kids

If my child asks, I'll answer. It's wrong for her to tell your son against your wishes though. Personally, I don't think it's wrong to explain it to a 6 year old. But it's your son so it's when you feel comfortable with him being told.

That's not ok for adults to decide what a child should or shouldn't know. She's out of line. Elementary school kids will ultimately ask on their own. Better for you to explain then kids on the playground of course. I believe I told mine moms have eggs they were born with. Dads have sperm they make all the time. They love each other so much the sperm fertilizes the egg and the mom grows a baby in her belly. I told them there's a special place the baby grows right below the stomach. When the baby is ready the mom goes to the hospital to deliver. Eventually they ask how the baby gets out and I am honest. Before fourth grade health class I told them about sex. Men have penises. Women have vaginas. It's like a lock and a key. Then I ask them if they understand what I'm saying. Inevitably they catch on and are bewildered. After they have health class we discussed a little more. I think you should tell your child whatever you feel most comfortable. My sisters found out from an idiot kid on the bus when they were in the 2nd & 3rd grade 😉

I don't think it's her right to tell your child about it, but I think that it's fine that they know. I knew all about sex at 6 in terms of, 'The man and woman have sex. The sperm meets the egg, and when it's fertilized, the mom grows a baby inside her.' In my opinion, that's age appropriate. I didn't go spouting off at school about sex, and I have a very healthy and open sex life, partially because I've never been scared to talk about it. When my daughter starts asking questions, I will be honest, but age appropriate for her. I'm not telling you what to do, though. I definitely don't think it's your sister in law's right to educate your child about sex, though. 

I tutor anatomy and physiology. We also live on a ranch where things live, breed, and die constantly. Sex is nothing to hide from a child in my opinion, as it's just part of life. It's the price of birth as death is the price of life. So I never hid anything. He doesn't need specific details, like the best way to eat someone for example, but he understands in mammals like us sex is needed to reproduce and is a form of bonding. He knews what a sperm and egg was at 6. It's all scientific basics. I understand it's your parental choice and she shouldn't be deliberately telling your child anything. I also am unsure of how it's "wrong" to exclude her own child or yours from her reproductive decisions. That's not really anyone's business but her and her partners in my opinion. But I don't blame her for not censoring out certain parts while discussing with her SO or explaining what's going on to her own child.

I think at about 9 years old is a good time to have the talk. I am going to be open with it with my kids because I personally don't think it should be hidden. But that's my personal choice and I think your friend is totally wrong for trying to explain this to YOUR child. 

I was 6 when I learned about sex, sperm, eggs, all that jazz. My mom was pregnant with my baby brother, I asked how it happened, and they told me. I already knew about penises and vaginas (helped change my younger brother's diaper when I was 3), and learning about sex was good for me.The earlier I learned things, the less difficult it was for me to ask questions as I aged.I don't agree with your sister explaining things, but your son is going to want to know more about his body and other bodies soon enough, I would suggest talking to him.Look up age-appropriate body books, and go through them with him. It'll be good for both of you. 

Prior to this point she had come to the conclusion on her own that a man and a woman get married and then they ask God to put a baby in the woman's belly. And we were good with her thinking that's how it went. I just wasn't ready to go beyond that in kindergarten :( I didn't know until 6th grade! I guess it's a different world we live in now.