no they aren't biologically related, they have different mothers entirely and yoon's mom cheated on her husband (taejoos dad's) with his brother but his dads "brother" isn't biologically related to his dad so neither parents have any relation to taejoo, yoon's dad is just someone taejoos grandfather took in after the death of yoon's dads parents and so thus raise him and taejoos dad side by side; which is probably how he encountered yoon's mom and then the affair began (inevitably conceiving yoon) - Hope that wasn't too confusing （/TДT)/ took me a minute to grasp too
Thanks, after reading everything I'm still also confused. lol
Yoon's biological mom is taejoos step mom
Yoon's biological dad is taejoos dads adopted "brother"
hope that is way easier to understand
What's the relationship of Taejoo and Yoon? Are they biologically related??