Pencils Providing Foreknowledge?

We are expecting 3 new additions (babies) to our family this spring & with that in mind, the pencil has been put to the test. Someone at one point & time passed along this information & it continues down the line. 2 of the 3 expecting know that they are going to be giving birth to baby boys. My cousin & his wife, however, have decided to not find out the sex of the baby in advance. We have been exercising the "pencil test" on everyone we know...those that are pregnant now, those that have already had kids (recently & long ago) as well as those that have never had a child. All of this in an effort to see which way the pencil will move. For those that are wondering what I am talking about, if you take a needle & wrap string, yarn or thread around it & then insert the point of the needle into the top of a pencil eraser, hold the pencil by the end of the string steadily over another lady's wrist without moving at all, the pencil will begin to move. If the pencil moves vertically on your wrist, it indicates you have had or will have a boy. If the pencil moves horizontally, a girl. Between each child, the pencil will rotate in a circle a few times. The pencil will also move in the birth order of the children. My mom's family swears by this test as do many other persons I have come in contact with. I have yet to meet someone that can say the pencil was wrong. The pencil will also show miscarriages, tubulur pregnancies, stillborns. If one was to have a child & give it up for adoption, that child is shown. My cousin, Chanda, has 3 children, 1 son (9), & two daughters (6 & 4). Between the birth of her son & oldest daughter, she had a tubular pregnancy (a son). The pencil moves boy, boy, girl, girl. When done on my mom, the pencil shows two girls which of course, is accurate. As my cousin, Lisa, went for her ultrasound to learn the sex of her baby due in May, she believed wholeheartedly it would say it was a boy. The pencil test also showed that she is having a boy. Just because I want to believe that a pencil can not know, I wanted her ultrasound to show a girl. Once again, the pencil was right...she's having a boy. So, when done on me, the pencil shows that I will have 2 boys. If only the pencil could let me know who is going to help me in making any child at all! I am sure that certain events must take place in order for me to conceive & for the test to hold true & so far, I think I am missing a major ingredient! Regardless, I just want to know where this idea came from long ago & what causes it to always be right. Some say it may be related to the amount of iron in your bloodstream, etc. If you hold the pencil over a man's wrist, it will do nothing. I've not seen a man be able to hold the pencil over a female's wrist & it work either. Something is very odd & mind boggling to me about the whole thing!