No, no, not those guys.
This guy, the guy those guys were named after:
Baptized on this day in 1674, the real Jethro Tull was a very influential British agronomist who invented several farming tools, and promoted more modern techniques of agriculture.
The band, by the way, did not adopt the name because they admired Jethro Tull, or even knew of him. In 1967, the band changed their name frequently to keep themselves playing in London clubs. Names were supplied by their booking agents. “Jethro Tull” was suggested by a history buff, and they happened to be playing under that name when they attracted attention. So they kept it.
Thus speaketh Wikipedia.