Connected or associated (7)
I believe the answer is:
related
This clue is a double definition.
'connected' is the first definition.
(similar in meaning)
'associated' is the second definition.
(relating is a kind of associating)
(Other definitions for related that I've seen before include "were sympathetic" , "Family members must be" , "Connected, by kinship say" , "Father and son have to be" , "Narrated; connected" .)