I have always been sychronized to the females living under the same roof with me. This started when I was a teenager. Swelling, cramps, and crabbiness. I always knew when my wife was pregnant before she did. I could somehow sense the changes in the estrogen level in her body.
Ok, say what you will, it is all my head. In my hypothalamus. I found this in my textbook over the weekend: "If testosterone is present during fetal development, certain specialized receptor cells in the hypothalamus become insensitive to estrogen; if estrogen is present, these cells are highly sensitive to levels of estrogen in the bloodstream." What does this mean? The threshold of central nervous system excitability determines whether there is a cyclic or acyclic pattern of pituitary release of hormones. If I got less testosterone and more estrogen while I was in utero, then I would be more sensitive to estrogen and my hormone levels would tend to cycle.