I wish I knew! It was from an online source (maybe familysearch.org or ancestry.com, not sure why I didn't annotate the fact). Duncan Clarke and Margaret Mckellar had (at least) Mary (1835-1869), Ann (?-1887), Elizabeth (?-?), and Duncan (?-?). Also looks like they had a son William born 1819 in Scotland. I have Elizabeth marrying "Black", no first name.

If true it may help explain why my Great Grandfather put "Ann Elizabeth Black" on his marriage certificate as his mother. Possibly she helped rear him when his mother passed away at age 6....

Earlier responder has Margaret Mckellar and William Mckellar with a father of the same name but different mother's name, born in Scotland. 1/2 siblings?... I love these mysteries. Also looks like Margaret had an earlier husband in Scotland (Neil Currie) who took first son born in Scotland (Archibald b. 1816) to Canada.