oomis, I disagree with your statement “the fact that five children can be brought up in the same loving home and one of them does not have good middos, can only be explained as that child having inherited certain bad characteristics from other members of the family.”
Like I said before, middos result from learned behavior. That behavior can be from parents, teachers, friends, and any other sources that one is exposed to. In fact, most likely everybody are exposed to a combination of these sources. Therefore 5 children can be brought up in the same loving home where 4 manifest good middos and 1 does not is explained by:
a) the 1 child being exposed to someone who did not demonstrate middos
and/or
b) every person has free will and despite seeing middos may choose their own path