Only slightly belated birthday wishes for Albert Einstein's 127th birthday.
Of course, we all know how Albert Einstein married his cousin. He had relationships with many women, but found them unsatisfying, especially (as he related) he found the large breasts of his cousin overwhelmingly attractive and this dimmed his interest in other women. As a result of this he theorised (even though genetics was not his primary field of study) that evolution predisposed to matings within family groups in order to increase the frequency of genes from those family groups. The attraction for large breasts was the outward expression of this drive. This theory is well known today as Einstein's Theory of Relative Titty.
(Originally sourced from all over the internet, but a whole group of good physics jokes are at Science Jokes.)
Albert Einstein was born at Ulm, in Württemberg, Germany, on March 14, 1879.