Making it up as I go along

sadie and laken are alway fighting--"laken hit me" followed by "sadie hit me" are common phrases heard at our house. there are definitely sharing issues involves in these confrontations--and a lot of time I rely on sadie to be the "bigger" person and share toys with her brother.
I know siblings are supposed to argue and not always get along--I remember my sister and I chasing each other around the house...but it seems to be constant here.
they still want to take baths together but someone always ends up crying... sometimes I wonder if it is because they are different sexes or their personalities are so different. dan tells me it will get better as they get older--I just don't know.
they do have their moments though like when sadie insists on giving laken a goodnight kiss, or laken gives sadie a cookie, or her blanket just because. I know they love each other--laken needs to know where sadie is every minute of the day--and sadie has to always open laken's door for him when we get in the truck. I just look forward to the day when they enjoy each others company more...