It's a Girl/Boy because

The other day my children had a debate. Tami (girl or 4.5 years) tells her bother (Linga, 7) that she is going to have a baby sister. Linga moves in quick and tells her that the doctor said she saw a boy so we are going to have a baby brother. Upne which Tami reiterates the "fact" that its going to be a girl because "Mum is the one carrying the baby". Clearly implying that if I was me carrying it, then it would be logical to expect a baby boy.

I was out of words and I just let the debate fizzle out. A few weeks later, Thumbiko, their baby brother, was born. After about two weeks Tami has accepted the fact and loves him to bits.

Question for parents and parents to be: what should I have told Tami?

Later.