Well, if that happened in fanfiction, it would likely create a major rift within the superhero group. It could also lead to some intense action sequences and emotional moments as Tony tries to defend himself and understand Bucky's motives.
Yes. There are unfortunately some true stories where a child has committed a heinous act of killing a girl. For example, in some cases of extreme abuse or mental instability in a child, they may act out violently. However, such cases are extremely rare and often shock the community due to the unexpected nature of a child being involved in such a serious crime.
There is no such general situation in real life where a 'kid' can directly 'kill' a 'gene' in the literal sense. Genes are part of our biological makeup and can be affected by various factors like mutations, environmental influences, and diseases, but not by a kid in a murderous way.
Hard to tell. True stories can be complex and vary greatly. Maybe you could provide more context or specific information about the story you have in mind, and then we could better determine if a kid killed the girl.