I have heard that according to Islam we should kiss the hands of our parents to show respect. Fatima (may Allah be pleased with her) used to kiss the Prophet (SAW) hands and give up her space for him to sit whenever he visited her.
However some people say that a younger person should kiss any older person's hand while some say it is haram unless the two people are mahram to each other and others say this ritual is only for between a child and his/her parents and grandparent.
Recently I heard that it is encouraged to kiss their parents feet/legs (without bowing or prostrating) However how can we put our head by someone's feet? Is this not a sin itself?