A child (offspring) is the result of the junction of the male and female gametes (sperm cell and ovum).
So, the genetically inherited traits, including appearance, have a mere 50% chance to be closer to one of the two parents.

Traits like eye shape, mouth shape, skin and hair color tend to be usually closer to one of the two parent's appearance. Often though a blend of the parents' characteristics results as mostly in the case of skin color; e.g. the skin color of an offspring of two parents whose skin color is different tends to be an intermediate skin tone.

In quite a few cases, a characteristic which has been 'dormant' in the two parents might appear in the offspring, e.g. two brown eyed parents have a blue eyed baby;
this is the case when a trait from the parents' ancestors becomes dominant in the phenotype of a 2nd generation offspring.

The inheritance of genetically transfered characteristics is the subject of the science of "genetics". The most famous pioneer of modern genetics is Gregor Johann Mendel, who studied the appearance of pea plants in the 19th century, long before there was any scientific correlation between genome and offspring appearance.