Esther Sayle was the youngest of a large family.
The deed of sale, presumably for just a small plot probably on which to build a house, predates his 21st birthday and not sure that it would be valid - he certainly waited until post 21 otherwise he would have needed a parent's or a guardian's consent (and would have solved your problems!) - interestingly in 1861 his next door neighbour was also an Irishman who married a Manx woman