If everything else is groovy except for your hamstring attachment, I'd be inclined to blame the shape of the saddle.
Some folks like pear-shaped saddles. (looking down at it from above, it has a gradual transition from nose to cantle. Kinda like a tear drop)
Some folks like T-shaped saddles. (looking down at it from above, it has an abrupt transition from skinny nose to wide cantle)
What works best for a person depends on a lot of things. One of them is certainly the unique placement and angle of the head of the hamstring.
Two riders can look exactly the same, ride the same width and length saddles, but need different shapes.
I don't know of any shortcut to deciding what shape a person needs. Just trial and error.
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