It could be that the apple doesn't fall far from the tree.
Ward Fowler was an actor who starred in the hit 1970's TV series 'Inspector Lucerne'. "Ward Fowler" was actually his stage name, as he had deserted the United States Army during the Korean Conflict and had been living in Canada since then under the alias. His producer, Claire Daley, had discovered his secret and had been blackmailing him. Ward Fowler finally had his fill and he killed Claire with the intent of making it look like she was a victim during a botched deli hold-up. Unfortunately for him, Lt. 'Columbo' figured it out and Fowler went to prison. (It was also hinted in the finale that the actor had gone slightly insane.....)
Fowler was single during the period in which the murder occurred, but that doesn't mean he wasn't married earlier; nor does it mean that he didn't have any kids. He may fathered a son around 1965, and that boy could well be Garrett Fowler. Garrett went into law enforcement in order to atone for his father's sins. At least... that's what he would tell people.....
It's also possible that a year earlier, Ward Fowler fathered another son whom he also named Garrett. This son also became a cop, probably for the same reason but he actually meant it. Although a rebel, the first Garrett was still a good cop, and he was put in charge of a team of cops with physical and mental challenges, as seen in the TV movie/pilot "Special Unit". (Naming both your sons "Garrett" is not as crazy an idea as you may think - remember, George Foreman named all of his kids "George"....)
An argument could certainly be made that the two Garrett Fowlers are related....
None of this is likely to ever come up in future episodes of 'White Collar', so Toobworld Central is content to let it stand.
Remember, this "Theory of Realateeveety" is just that - a theory.