Your Y-DNA would not tie to Anderson. Your grandmother's DNA would not either. Please read DNA 101 at the Clan Blair site for more information.... use a search engine to find it.
Please also join the Scottish Clans DNA Project and share results. You will find us at Scot-DNA@rootsweb.com
Lauren M. Boyd, FSA Scot
Clan Anderson Board Admin
Team Member, Scottish Clans DNA Project
Scot-DNA List Admin