Bava Batra 155: Old Enough for Business Sense

More on the case of a possible minor as the heir who then sells the inheritance property. How old must one be to emerge from the "minor" status in this context? Physical maturity? 13? 18? 20? 35? Also, does a 14-year-old girl know the ins and outs of commercial dealing? If she does, her property transactions are valid. But why is this case about a girl? (Because it happened with regard to a girl). How much vested interest goes into the concerns of whether a sale is valid, beyond the individual's maturity? What about people's personalities? Does chutzpah indicate a lack of business sense, for example?