When my son was quite young he initiated a conversation about adoption this way . . .
"Mom, is there a law that says a person HAS to have a baby?"
"No, son, no one HAS to have a baby."
"Then, is there someway for people not to have a baby?"
(Oh, dear, birth control at this young age!)
"Yes, son, there is a way. It is called birth control and there are several different kinds."
"Well then, if there isn't a law that says a person HAS to have a baby and if there is a way for people NOT to have a baby, then why would a person make a baby that they can't keep. Why would you make a baby and then give it away?"
"Well, son, no one gets up in the morning and says, 'Today I'm going to get pregnant and have a baby and then give it away.' It doesn't happen that way."
"How does it happen?"
"Sometimes it is because two people like or love each other and want to have sex and they don't make good plans not to make a baby so that's what they end up doing."
"Huh, well I'm never going to do that! I'm never going to make a baby unless I want it and can take care of it!"
"Well, son, I hope you remember that. Someday, maybe when you are around 15 to 18 years old, and your hormones are making you look at your girlfriend with desire, then I hope you remember what you just said. Believe me, it can happen in an instant."
Many years have passed since that conversation and I truly believe that he didn't ever forget what he said.