Really they don't need much for an answer. Answer to the level of their ability. For her you might try that when 2 people love each other very much they have so much love that it makes a baby. And it needs to grow in a special place in mommy's tummy and the doctor helps them come out when it's time for baby to be born. But if she's anything like my kid she'll want to know more. We have a body book for kids that touches gently on reproduction and he was satisfied with learning that moms have a uterus where the baby grows lol!