There is this 1861 census entry on Scotlands People
HOOD ROBERT
1861 M age 4
586/ 1/ 31 DALMELLINGTON AYR
I cannot see it on Ancestry - but it seems a possible for your Robert.
I know the age is not quite right, but did his guardians know his correct age?
Sofee, you might need to spend some credits on these census records from SP to get the full picture.
I would start with the 1871 census (as posted directly above) and find out what it really says for that Robert Hood - I feel quite certain that he is your Robert.

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Thinking
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Elizabeth Torrance (nee Barclay) died Kilwinning 1858 (age 78) mothers name Cowan
- I wonder if she might have been looking after young Robert Hood up to her death? and then he was under the care of her unmarried sons / Roberts uncles.