There are 4 of them. Correct me if I get their names wrong. 1. Joe Jonas 2. Kevin Jonas 3.Nick Jonas 4. Frankie Jonas (he isn't in the band, they call him 'The Bonus Jonas') But they had no sisters
There are 4 brothers and 3 sister's all up. Assume your one of the brothers - hence you have 3 brothers and 3 sisters. However any one of your sisters, would have 4 brothers and 2 sisters.