These days, at least in America, families are small. Even what I would consider a small family like mine with four children is looked on as big, which is kind of crazy to me, but it is what it is.
In years past, a family with only one or two children was not only uncommon, in many cases having a lot of children was seen as extremely important. Farmers needed a lot of people to work the land and a lot of children died young of a lot of things. My dad was one of seven, his mom one of ten. Both of my grandmas lost a brother before he reached the grand old age of three. For one grandma that meant she never met one of her brothers.
In more recent years I knew a family with nine children, two of the girls in the middle being around my age. If I remember correctly, they only had one boy. This dialogue prompt is probably something he’s heard over the years.
So how many sisters would get this kind of reaction? Is eight enough? Who is reacting this way and to whom?
I do have a character who probably gets this sort of reaction. Including one adopted sister and seven half sisters (plus two half brothers), he has eight sisters and two brothers when all is said and done. As he didn’t grow up with them other than the one adopted sister, it certainly came as a shock to him when he first met his biological dad and learned just how many sisters he had.
Personally I love writing big families. It’s fun seeing how all those different personalities interact and how they react to being related to someone they don’t always care to even be around. What kind of situation would bring about this particular statement in your story?