Today's Free Genealogy Tool is an unusual one. Your mirror.
Go on, take a look. Do you see a pair of blue eyes looking back at you? If you do, then you're related to Frank Sinatra -- Ol' Blue Eyes himself.
Genetic researchers, back in 2008, published a ground-breaking paper showing that all blue-eyed people are descendants of a blue-eyed common ancestor. What's more, the blue-eyed branch of the human family is a fairly new development, from a genetic point of view, arising perhaps as recently as 6,000 years ago.
The blue-eyed mutation arose in Europe, possibly in the area of Afghanistan. Prior to that time, scientists theorize that all humans had brown eyes.
Of course, six millennia is a good stretch of time, so your relation to someone else with blue eyes is likely to be many, many times removed. Still...there's some sort of family connection there. If you see a fellow blue-eyed person, feel free to call him or her cousin.
You can read more about it in this nice write-up in USA Today on blue-eyed genealogy.
Or if you prefer, you can dive into the original paper itself, though it's really only for hard core geneticists. Just look for the one with the title: Blue eye color in humans may be caused by a perfectly associated founder mutation in a regulatory element located within the HERC2 gene inhibiting OCA2 expression.
Sinatra not your type? If you prefer, you blue-eyed types are also related to Brad Pitt. And Marie Curie. And Paul Newman. And...
Don't forget to also check for your family history at Ancestry.com and NewspaperArchive. These are subscription databases, but they are among the most powerful research tools available for looking into family roots.