Answer:
They each have a reading that repeats a sound.
父 FU, chichi - father
留 RYUU, RU, to(meru), to(maru) - fasten, hold, stay, settle
畳 JOU, tatami, tata(mu) - straw mat, fold up
闘 TOU, tataka(u) - fight, struggle
唆 SA, sosonoka(su) - tempt, entice, incite