^are you curious about your half brother? Did you do any searching/ Googling? (just curious)
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One of my high school classmates found out that her dad had a 2nd family/ that she has a half-sibling when we were in our 20s. The 1st family only found out when the dad died (in his 50s) and left something in his will for the half-sibling & the mother of the child. The 1st family (to which my classmate belonged to) were all gobsmacked. The half-sibling was less than 10 yrs old at that time. Their family drama was soap opera level.