Islam is a religion of mercy which is highly demonstrated to the weak; children of the most powerless people who need kindness and tenderness. It is worth mentioning that the Prophetic Sunnah obliges Muslims to show mercy to children, and makes kindness to them a proof of the goodness of their hearts, and assigns different signs for such mercy, like kissing them. In this regard, Imam Bukhari narrated on the authority of Anas, may Allah be pleased with him, that the Prophet, peace be upon him, carried Ibrahim, kissed and smelled him.
Imam Muslim narrated on the authority of Anas, may Allah be pleased with him, who said: «I never saw anyone more kind to children than the Messenger of Allah, peace be upon him».

It is worth mentioning that this mercy was unusual at that time. Imam Muslim narrated on the authority of Abu Hurayrah, May Allah be pleased with him, that Al-Aqra 'ibn Habis, saw the Prophet, peace be upon him, kissing Al-Hassan, then he said: I have ten children and I have never kissed any of them. The Messenger of Allah, peace be upon him, replied: (Allah’s mercy is granted to those showing mercy). At other narration by `Aishah, may Allah be pleased with her, the Prophet (PBUH) said: (Then what can I do if Allah has deprived you of mercy)

The Messenger of Allah, peace be upon him, made mercy for children and kissing them a sign for mercy in the heart of the Muslim.
Let this mercy be our way on dealing with children in general and ours in particular.

http://300035.dotdothktrade.tech/en/artical/3407687/293-Sunnah-kissing-children