Answer is Independent assortment.
Fraternal twins each come from their own egg and sperm. Hence, these are dizygotic. Just like any brothers and sisters, fraternal twins will share about 50 % of their DNA. Each person receives half of their DNA from mother's egg and the other half from father's sperm. Fraternal twins may or may not share similar characteristics due to Independent assortment of genes occurs during meiosis. In meiosis the number of chromosomes in a parent cell is reduced by half to produce four reproductive cells or gametes. During meiosis, the pairs of homologous chromosome are divided in half to form haploid cells. The assortment or separation of homologous chromosomes are random.