Number of sets of twins in primary school

[SerialMover]

Was speaking to a teacher friend of mine the other day about the number of sets of twins we have in my children's primary school, and she thought it was a large number, something I'd never really thought about before, so I thought I'd see if our school was unusual or not...

DC 1 - 2 sets of twins (B/G and GG)
DC 2 - 1 set (BB)
DC 3 - 2 sets (B/G and GG)

plus 2 sets that I can think of in reception, and 3 sets in 2 other year groups, there may be more! So at least 10 sets in a 2 form entry primary.

How many sets of twins/multiples does your school have?

I know loads of sets of twins including my best friend who had B/G twins. All under 30 when their twins were conceived naturally and they had had 1 or 2 singletons before the twins. I thought the other day, why do I know loads of twins? They seem to be increasing.

In the school I worked at we had 2 sets of identical twins in a year group of 15.
No others before or since in the school the whole time I worked there.