I've had a boy for 5 months and a girl for 6 years and honestly? So far, in the baby stages, no difference in temprement. My daughter was a calm, happy, 'easy' baby and so is Seb. The main difference is their sizes. Seb is a lot bigger than DD was, takes more milk, weighs more and is longer than she was. Also, Seb had colic and DD didn't. Apart from that they're practically the same baby!