I mean, really, what does it mean to "act human?" Human behavior encompasses everything from Gandhi to Hitler, from Mother Theresa to Jack the Ripper. It hardly makes sense to assume that human genes would make an individual act less aggressive or more timid.
But... But, in the Doctor Who episode "Evolution of the Daleks", it shows that if you combine a Dalek and a Human, it will be a very gentle and peaceful being thanks to it's human... stuff!