the.com/sibling
your first rival, your built-in witness, the only person who remembers the crime with you
shared dnaFull siblings share about 50% of their genes
birth orderFirstborns score marginally higher on IQ tests
oldest bondSibling relationships often outlast both parents and spouses
deep historyVertebrates have had siblings for over 500 million years
twin trickIdentical twins share fingerprintsbut still differ slightly