The horse thief

Me old granddad insisted it was true, and who am I to argue with me old granddad?
We get called Cosgrove a lot. We do. It's a natural enough occurrence. The name, she's close to Cosgriff, but Cosgrove being a bit more common, folks gravitate towards it. We get that. But we resent it too. Cosgrove, you see, he stole horses. A horse thief he was. A scoundrel if there ever were one.
Me granddad, he told a tale of the family which dated back to the old sod, to County Tipperary. Why the Irish be so concerned with not merely bein' Irish (who'd not want to be Irish, I ask ya) but with bein' Irish down to the county, well, there's a certain sophistication to that which most of the world cannot understand, their not bein' Irish and all.
So the tale goes, real short here, is that in years gone by we were Cosgroves. Real, true Cosgroves. Then one of them old relatives, he decides that making an honest livin' did nothing to suit him. Dishonesty was his call. Dishonest beyond covetin' someone's property but actually absconding with it. In his case, their horses.
That were bad. Real bad. Folks needed their horses, they did, for plowin' and travelin' and gettin' into minor mischief well short of horse thievin'. That could not be tolerated.
You could not be associated with such foul people and keep your good name. So you change your name, make a good new one. With us, it was to Cosgriff. Cause we could not in no way be associated with a horse thief.
Me granddad insisted it were true. Who I am to doubt such a tale?