baptism for Thomas Smith JOHNSON from May 6th 1840 which states that mother's name was Elizabeth SMITH and father's name was Matthew JOHNSON.
What date was given for Thomas' birth & what date was it registered?
If Matthew was Thomas' father, why didn't he sign the official birth registration?
Did Matthew have an occupation which took him away from home which meant he wasn't at home when Thomas' birth was recorded & was going to be away for a duration?
Why, if he was 'away' was the birth not amended to include his name on his return or at a later date?
Was Matthew in attendance at Thomas' baptism?
It appears to me, Matthew & Elizabeth met while she was 'with child', they decided to marry prior to Thomas' birth & Elizabeth has named Matthew as 'father' on the baptism of Thomas, possibly unknown to Matthew?
It then seems, at a later date, after Thomas married, there was a reason for the 'truth' to come out & Thomas learned Matthew wasn't his biological father?
As has been mentioned, DNA may be the way to find the truth?
Annie