People born together have hereditary unit to share (10)
I believe the answer is:
generation
'people born together' is the definition.
I can't tell whether this definition defines the answer.
'hereditary unit to share' is the wordplay.
'hereditary unit' becomes 'gene' (I've seen this in another clue).
'to share' becomes 'ration' (a ration is a share of a limited resource).
'gene'+'ration'='GENERATION'
'have' is the link.
Can you help me to learn more?
(Other definitions for generation that I've seen before include "production" , "what was lost in WW1" , "Everyone of same age" , "peer group" , "group of similar age" .)