Just having others around though isn't always the key. Are those adults (I assume they are your parents) comfortable about working with snakes? Will they be there to care for your snake if you are away at a school or social committment? Make sure and have those conversations before you commit to the years of care this boa would require. A male common boa though, conservatively fed isn't likely to cause you a lot of problems size wise.

My own son, Luke, got his male BCI when he was 14. His male boa was just a few months old and they've matured together over the past 3 years. Severus, the boa, isn't a big male and has never been powerfed so he's grown slowly. He was well socialized as a baby and we've continued that by encouraging our son and our entire family to handle Sev with gentle, firm and calm handling techniques. I'm thrilled to say this is a snake that has never nipped, heck he's never hissed at us LOL.

I would suggest you purchase your boa young but well started from a good boa breeder rather than a pet store. Pet stores ask a ridiculous amount for a common boa constrictor and do not really properly care for them or socialize them at all, let alone sex them correctly if at all. A good boa breeder I think would be your better bet. You and your parents could express any concerns and ask questions to that breeder before you make the final decision to buy a boa.