Why does Marmalade hate Pumpkin?

Cats have different personalities just like people. I have four cats and have a quite dynamic relationship with each cat. Logan came first and helped me raise Tucker, Hemingway, and Deuce. They all love Logan and Logan loves them (I think because he's the boss). They will occasionally fight with Logan, but quickly make up. Hemingway is the black sheep of our family. I think it's because she has chronic allergies. They torment her to death, but if she starts sneezing Logan will go tend to her. She is rather aloof, but will sit on a knee if offered (as long as you don't pet her.) Tucker loves Logan, but I've never seen him hang out with Deuce. He also doesn't like me very much, but loves my husband. Deuce is a little wench and picks on everyone. She is also the people oriented cat and has to sleep touching me at night or kneeding my pillow. Deuce and Hemmingway are mortal enemies and will fight if they are in the same room. This relationship even extends to our dog. Ra doesn't really like the cats, but Tucker and Deuce love him. When he comes inside for the evening they will give him numerous "cat hugs" which he nervously accepts. He will growl at these two when they try to snuggle with him at night. He really doesn't like it when Logan tries to groom him.

Are they all the same sex? if it's two males and a female or the other way around it could be dominance issue