I don’t believe you’ve presented anything to support this conjecture other than a few cherry picked anecdotes. My gut feeling is that it isn’t true to any significant extent.
Here’s my ranking system. Say there’s a burning building with all my friends and loved ones. Each time I go into the building there is a very real chance I will burn or choke to death. For some reason, they will all die unless I go in to try and rescue them. I can only save one at a time. Here’s the order I save them:
- (Hypothetical Children… someday when I have them, they would be first)
- Mother
- Sister
- Father
- Boyfriend
- Best Friend
And here’s who I let burn:
Pets, friends, aunts, uncles, cousins, grandparents, coworkers and everyone else.
I believe at least part of protoboard’s conjecture. That is, if someone I love deeply – one of my kids, my wife, my baby sister – committed a horrible crime, I’d still love that person, even though I might feel morally obligated to turn her or him in to the police. And in many cases my love-created loyalty wout outweigh my senses of morality and civic duty. If my wife stole a million dollars from an orphanage I wouldn’t drop a time on her (though we’d probably break up). If one of my kids, years from now, drove drunk and killed someone, but somehow had not been caught, I wouldn’t turn him or her in.
I’d encourage them to turn themselves in, but if they didn’t I would. Loving someone IMO doesn’t mean protecting them from the bad consequences of their actions. I don’t think that means I wouldn’t still love them.
re ranking, do you issue weekly or monthly charts to friends, relatives and pets to let them know if they’ve moved up or down?
The highest level is for spouse, children, and parents.
Siblings, grandchildren, and dog are in the second level.
Other blood relatives and favored in-laws are in the third level.
The rest of the universe is in the fourth level.
What about if your wife did [something very horrible] to one of your kids? Or vice versa? Or to you?
Hitler gets his own level, surely.
Godwinized 
Anyone who gets involved with me knows damned well it will be a threesome – him, me, and the Roman Empire.
He also knows better than to ask me for the league tables in that situation as well.
(I have no family or close friends by choice, so there really aren’t any extra factors unless you include my little cat who is a completely different situation altogether.)
Do SERIOUSLY put your dog over your blood relatives?
I guess I’m a speciesist, then, because even though I grew up with a dog in the family, there’s no way I’d rank an animal over my blood relatives. With the possible exception of my… uh, nevermind.
Between my dog and my nieces, sure I love my dog more. How can you love someone that you didn’t grow up with and see once a year more than you love someone that spends every day with you and gives you unconditional love?
Simple: A dog is an animal, not a human. By default, I value a member of my own species over an animal. Even if that animal is the dog I grew up with.
Yeah, I don’t even like my dogs that much. We tolerate each other.
I use colors. Blue means “I’d love you even if you were Jeffrey Dahmer.” Green means “I’d wipe your ass if you had a debilitating disease, but my love is still conditional upon you not committing capital crimes.” Yellow means “I’d lend you significant sums of money, but you will have to find someone else to wipe your ass,” all the way down to purple, which means “You can crash on my couch if you are in the area, but I can’t drive you anywhere, and you can forage in the fridge, but I’m not cooking anything special for you.” Black means “Who are you exactly?”
I issue updates monthly, so people know where they stand, and give notes on what the reds and purples can do to move up.
I just publish a weekly newsletter with photoshopped depictions of who is burning alive and who I’ve rescued.
Wow - this is so individualized and difficult to generalize. Everyone’s situation is different.
I’m definitely an outlier. I was the only child of only children. I married an orphan. I have two sons, one daughter-in-law, a brand new preemie grandson, three dogs and one cat. My husband’s deceased and I have no significant other.
With so few people in my sphere, I’ve got enough love for all of them pretty equally, but if I were able to rescue them one at a time from a burning house, with less and less chance of success for each, I’d go in this order:
Grandson
Older son
Younger son
Daughter-in-law
middle dog
youngest dog
oldest dog
cat