If you find yourself interested in a colleague's son who is much younger, it doesn't mean you have special feelings for him. Instead, it may just be a simple act of appreciation and liking. In this case, I advise you to remain calm and professional and try to communicate with this colleague in an appropriate manner.
First of all, you need to be clear about your professional ethics and ethical standards. No matter how strong your interest in this child is, you should respect his family and privacy. Do not attempt to engage in any inappropriate contact or behavior.
Secondly, you can try to have a more friendly relationship with him. By communicating with him, completing tasks together, or sharing some professional experience, you can get to know him better and build friendship and trust. This can help you better deal with this emotional distress.
Finally, if you feel like you can't control your emotions or feel that this interest has taken a negative toll on your work and life, then you may want to consider seeking help. You can consult your company's HR department or a counsellor for better advice and support.
In conclusion, it is essential to be cautious in everything and to remain calm and professional.