My 7 yr old b/g twins know that egg meets sperm and a baby is made. They recently asked about how they join together. I said the man puts his penis in the woman's vagina. They said that was gross and it was the end of the conversation.
Going forward for more in depth discussion about how their bodies will be changing, puberty, etc, how should DH and I handle it? All 4 sit down together and go over things generally? I talk to DD and DH talks to DS? I want the kids to understand what both boys and girls are going through and to be able to ask questions to either DH or I.