Hello,
I am looking at childless men in the UK and I am using panel data which has 9 waves. childlessness is defined as not having a biological children at age (x). I need to create the dependent variable which is (childless) and that is those men who have not had a biological child by age x. one way to get the age cut off is to look at the age of first child and then deiced the age cut off of childlessness.

I have my panel as this
wave pidp (individual id) hidp (household id) (varlist)

I have these variables in my dataset:
year of first child
fathers'birthday
men

I did this command:
gen ageatfirst= year of first child -fathers'birthday

i think I need to use the hidp to do this command is that right? any advice please