Wow, you must be quite proud of your son/grandson/greatx grandson!
Noun 1. descendant - a person considered as descended from some ancestor or race
descendent
child - a member of a clan or tribe; “the children of Israel”
relative, relation - a person related by blood or marriage; “police are searching for relatives of the deceased”; “he has distant relations back in New Jersey”
scion - a descendent or heir; “a scion of royal stock”
ancestor, antecedent, ascendant, ascendent, root - someone from whom you are descended (but usually more remote than a grandparent)