Complex sentence: Additionally, the 2D:4D ratio has been shown to be affected by variation in the androgen receptor gene and the ratio of testosterone to estrogen in amniotic fluid is found to be negatively correlated with the 2D:4D ratio.
Split into simpler sentences: Additionally, the 2D:4D ratio has been shown to be affected by variation in the androgen receptor gene. The ratio of testosterone to estrogen in amniotic fluid has also been found to be negatively correlated with the 2D:4D ratio.