Left follows right…right follows left…night follows day…animals follow their instincts…and younger siblings often follow their older siblings down the same career path; sometimes with remarkable results. Look at Charlotte, Emily and Anne Brontë; or, Orville and Wilbur Wright; John, Robert and Teddy Kennedy; Britney and Jamie Lynn Spears; Ulysses and Cary Grant. My older brother is a Population Geneticist.