Not true. HOWEVER, it is true that, in the case of UK/Irish surnames, clan-based surnames tend to have fewer distinct genetic groups than other common surnames. In most of the clan-based surname YDNA groups, you find a handful of very large distinct groups, often distantly related (pre-surname era but post-B.C.). While with most other common surnames you find dozens and dozens of totally unrelated groups (unrelated within at least 1000 years). This makes sense, since most clan surnames derived from a single clan, while most other surnames were adopted in lots of places by lots of unrelated people (eg, Brown, Smith, Field, Carpenter, etc).