Is it ok for parents to kiss their children on the lips, and in public? Example: Mother kissing her's son or father kissing his daughter?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

There is evidence in the Sunnah that it is permissible for the parents to kiss their children. Imaam At-Tirmithi reported that 'Aa'ishah narrated that when Faatimah enters to the Prophet [and she was his daughter], he would stand and kiss her and make her take his seat. When the Prophet enters to her home, she would stand and kiss him and make him take her seat. When the Prophet was sick, Faatimah bent down and kissed him and then she raised her head and cried.

As regards the parents kissing their children exactly on the mouth, if the children are young, then there is no harm in it. Al-Bazaar and At-Tabaraani reported the story of the killing of Al-Husseyn that Anas said: "I saw the Prophet kissing him where you are putting your stick." [He said this to 'Abdullaah Ibn Ziyad when he was putting his stick on the mouth of Al-Husseyn ]. However, the scholars disliked a man kissing his female Mahaarim (non-marriageable relatives) on the mouth, or a woman kissing her male Mahaarim on the mouth lest desires which lead to committing what is forbidden would be incited. This is the view of Hanbali school. There is no doubt that this is a sound opinion especially nowadays where corruption is widespread even among the Mahaarim. What is worse is that there are awkward movements which propagate incest through the different audio and video means of subversive mass media.

Therefore, a man should not kiss his grown daughter on the mouth and a mother should not kiss her grown son on the mouth to avoid any means that could lead to corruption.

Allaah knows best.