The lines of the palm are not formed because of folding the palms or the movement of our hands. There are three reasons for this. 1) If the lines are formed just because of folding our palms, then you should see only horizontal lines in your palms since you can fold your fingers down towards the inner palm. But, there are also lines that pass vertically in your palms. 2) If the lines are mere marks of movement of muscles then a manual laborer who works more with his hands should have more lines than those of a person who does sedentary jobs. But, in thousands of cases, it is proved that the laborers have very few lines. 3) The lines in the palm are formed by the time the fetus is 10 weeks old. But the muscles to fold the palms are formed after 11 th week.