I think it's common among Korean families for the mother to be overbearing. It was kind of funny, b/c when my parents found out I was dating a Korean guy they said, "OMG, Koreans beat their wives!" When my DH (then boyfriend) and his brother heard, they were rolling on the floor with tears in their eyes. They said, "If anyone is beating anyone in this house, it would be mom beating dad!" So, yes, my mil is an alpha-female, but she held that title even before my sil and I came into the picture.
She has always demanded the full attn and admiration of fil and her two sons. As soon as bil and my DH both got married, my mil got busy doing everything in her power to challenge her son's marriages by trying to make them choose her over the dils. She caused a lot of trouble in both marriages for the first few yrs, BUT the turning point was after both sons started their own families. My sil continued to put up with mil until she had her 2nd child (a girl, my mil hates girls, she even told sil and I that she was so happy she didn't have any dd's), and mil basically crapped on sil and niece one too many times and bil finally stood up to his mom, b/c the way she was behaving was just deplorable. For me, it was after I had my first baby, my DH started standing up to his mom, but we were married for five yrs before we had children and during those five yrs, mil was just awful and I would say that 90% of the arguments that my DH and I had at that time, stemmed from his mom causing trouble btwn us. I still resent that my DH often sided with his mother during our pre-children yrs of our marriage. It was always, "Why are you so mean to my mom?" "You made my mom cry." "You should feel sorry for my mom." I hated it. Now he realizes how manipulative his mother is and when she starts up with her act, he puts a stop to it right away. However, she had him eating out of her hand for most of his childhood and early adult life.
I still do not like my kmil (and I do not think I can ever forgive her for the things she has said/done to me), BUT she has improved a lot in the past few yrs. I think she finally realized that her sons chose to stick up for their wives, not for her. She is upset about this, but in some ways I think it has put her in her place and she knows that if she tries anything, that instead of gaining favor with her sons, she will just further push them away. She has always been very selfish and the type who is envious and jealous of others. My mil doesn't have a good marriage (she blames fil, but really it's not fil, he is an exceptionally nice guy, SHE is a total BITCH to deal with, I don't think anyone could be happily married to her and I really don't understand why fil hasn't divorced her), and when she sees that her boys are happily married, instead of feeling happy for them, she feels jealous that she doesn't have the same thing and takes it out on the dils. I can never tell my mil that my DH did something nice for me, or she immediately becomes bitter and angry. For our first wedding anniversary, my DH went to Amish country and bought me a very nice handcrafted Amish wedding ring quilt. I made the mistake of showing my mil, not realizing that it would just cause her to get upset. When she saw it, instead of being happy for me, she became very upset and said that she never got anything like this from fil and how awful fil was, etc.. I have learned from that exp and from others, that I cannot tell my mil anything good that has happened, b/c she always turns it around and plays victim and it becomes a bitter, pity party for herself. She is incapable of feeling happy for other ppl, when she sees other ppl happy, her reaction is to become jealous of them and to think that it's not fair that she doesn't have the same happiness.
Oh and fwiw, I think that females in general are just catty to one another. I mean, alpha-female exists in the workforce as well. I'm an RN, and when I was working I NEVER fit in at work, and was often treated poorly by other female staff for whatever reason. Younger, prettier, well-liked by patients, b/c I actually treated my patients nicely, etc.. On one unit I worked at, I found out that my nickname from the nurses on the other unit was, "the nice nurse," b/c all other nurses on my unit were so nasty and rude, that nobody ever wanted to deal with them and I was the only nurse that anyone, including patients and nursing staff on other units actually wanted to deal with. In fact, that is how I got recruited onto another unit, b/c I was sick of being treated like garbage from my own unit's nursing staff, and of course when they found out I was leaving, they had nothing but nasty things to say and they told me I would hate it and come crawling back (didn't happen!). If given the choice, I would almost always choose to work with the male nurses, b/c I didn't have to deal with the gossipy, catty, female bitchiness that I would often have to deal with when it came to the female nursing staff. MANY of those nurses who were mean to me were older, like probably closer to my mom's age, those who were divorced, recent empty-nesters or never married. Sometimes I think that at a certain age, some women just become mean or something. There seem to be a high # of women in their 50's, who are unhappy with their lives and jealous of younger women, and they seem to get enjoyment out of trying to, "bring down" younger women. I've noticed my mom started to act, "mean" in her 50's, it was like she wanted me to go through all the crap she had to go through and is over-critical. One of my friends had the same exact experience with her mom as well.