Can you define “tomboy” more specifically? It’s hard to do a scientific study on an ambiguous descriptor like that instead of specific, quantifiable traits and behavior.
That said, testosterone is associated with higher masculinity scores on sex role inventories. These inventories ask people whether or not they identify with traits that are generally associated with masculinity or femininity.
Testosterone is also associated with higher scores on a dominance inventory in women, which may be considered a masculine trait, and is associated with more violent crime in women (relevant because the vast majority of violent crimes are committed by men). Also, testosterone correlates negatively with maternal drive.
Some, but not all women with excessive body hair have elevated levels of androgens, including testosterone.
Keep in mind, though, if you’re talking about children, their circulating levels of all sex hormones are quite low. The differences I described above likely do not emerge until puberty (all of the linked studies were on adults).
That does not rule out the possibility that testosterone and other sex hormones in utero contributed to differences in brain development, which can contribute to differences in behavior.