Question

why do siblings in a family sometimes have different traits?
siblings inherit traits only from their father.
siblings inherit different sets of alleles from their parents.
siblings inherit traits only from their mother.

Explanation:

Alleles are different forms of a gene. Siblings inherit half of their genes from each parent. Since parents have two copies of each gene (alleles), and each sibling gets a random combination of these alleles from both parents, different sets of alleles lead to different traits. For example, if a parent has alleles for brown (B) and blue (b) eye - color, one sibling might inherit B from the father and b from the mother (Bb, brown eyes), while another might inherit b from the father and B from the mother (Bb, brown eyes) or b from both (bb, blue eyes).

Answer:

Siblings inherit different sets of alleles from their parents.