How do you have 2.1 children?

Answer 1

just a phrase referring to the average number of children per household - not sure if it was the UK in the 80's or 70's but something along those lines

Answer 2

Having 2.1 children is not literally possible. The figure 2.1 is often used in statistical analysis to provide an average number of children per woman in a population, accounting for cases where some women may have fewer or more children.