Usually girls are said to be more mature mentally than boys of same age so is it a gud decision to marry a boy of same age?

It seems to me that maturity greatly varies from person to person and there'd be little reason to believe a random girl is at all significantly more likely to be more mature than a random guy of the same age. That said, the decision to marry should be based on what each person actually knows about the other and not on some rule of thumb. As far as I can tell, there is no reason to suspect people of the same age will have a less successful relationship.