if you top the plant will it change sex?

[HAWK]

A year or so ago I bought an old phototron to grow "tomatoes + iron" and redesigned it with an ebb&flow tank, different lights, a tank heater, an O2 fan and water bubbler and it only added 2cuft to the size, it started to work well but the tomatoes started to grow up instead of out and went right throught the fan, what a mess!! I would like to know how to make a "plant" bush instead grow up, I heard if you top the plant it will change it's sex and be useless, if you top it again will it change back?????