If quarks always exist in pairs then why do protons and neutrons have three quarks, not four?

If you were to create a proton, you would have to create three anti-quarks making up an anti-proton. Thus, creating quarks and antiquarks.

Explanation:

When you heard that quarks come in pairs, it meant that for every quark you create you must also create an antiquark. Thus, if you were to create a proton, you would have to create three anti-quarks making up an anti-proton. Quarks have three colors (red/green/blue). Antiquarks have three anticolors (antired/antigreen/antiblue). The principle of color confinement lets the colors "cancel". This produces three simple arrangements: a quark/antiquark pair of the same color, three quarks of all different colors, or three antiquarks of all different colors.