Sentence:  His <WSD>nonassumption</WSD> of the Baronetcy certainly throws some doubt on the validity of his mother's marriage, but the issue thereof was recognised by the parents of the father, whose mother, “Noble Marie Kinloch, neé de Rochead,” was, in 1732, sponsor to the 1st child, and whose father 9the 4th Baronet( as a sponsor, in 1733, to the 2d child" etc. 
Meaning of the word marked with <WSD> tags:  The failure to take up, adopt, or take responsibility for.