Men say that each brother has several sisters, which means that there are more boys than girls in their family 1.

When a girl says that her brother is twice as big as her sister, it means that there are two girls left (more 1 boy, and one less girl is equal to 1 times of the other girls).

So girls have 2+ 1=3, and boys have 3+ 1=4.

There are four brothers, three sisters and seven brothers and sisters.