The other morning when I was walking Angus, a runner stopped to admire his ears.

Angus has adorable ears: They look like they want to stand up but instead collapse endearingly to the left. He always looks like he's in a stiff breeze.

It was those ears, actually, that got me wondering a while back about his lineage. I knew a little: His mother was a stray, rescued by LightShine Canine from the Pine Ridge Reservation in South Dakota. They handed off the mother and her five tiny puppies to Heart of a Border Collie rescue in November, and Angus found his way to us in late December. He was just seven weeks old.

The rescuers guessed that he was a mix of border collie and Lab, which sounded good to us — all of our previous dogs had been either border collie, Lab or a mix of the two.

Angus has the border collie blaze of white on his nose, the sleek black coat of a Lab, and adorable white border collie socks. But his head — isn't it just a tiny bit blocky? And those sloe eyes, slightly tilted in his face — those don't look familiar. And those goofy ears! Where'd they come from?

So we bought a DNA kit.

Angus’s mom, Bonita

We had done this before, with our six-year-old, Rosie, and with Riley, our previous dog. It's a trick, let me tell you, to swab the inside of a dog's cheek. But through the DNA test we learned that Riley (who we had guessed was springer/Lab) was almost full border collie, and that Rosie was mostly Lab (no surprise there), cut with harrier.

Angus submitted to the swab (more or less), we mailed it off, and we waited.

And while we waited, I got an e-mail from a woman in Stillwater who has been reading about Angus in the Star Tribune. "Hey, Laurie!" she wrote. "In January I adopted Bonita from Heart of a Border Collie and it turns out Angus is one of her puppies. It's been fun to read updates on his life! Bonita is a dream dog — very sweet, super smart, playful and affectionate."

She sent several photos of Bonita, and my gosh she looks an awful lot like Angus — white chest, audacious ears. So the mystery of his mother was solved, but who was his daddy?

The DNA test results came back, and they were a surprise. On one side, 25 percent cattle dog and 25 percent a mix of border collie and German shepherd. That was Bonita.

And on the father's side? One-quarter so many breeds they couldn't tease out much, and one-quarter American Staffordshire terrier. This explains Angus's blocky head.

Still, I wasn't sure I trusted these results. Only one-eighth border collie? No Lab at all?

So we did it again. We bought another kit, we swabbed his cheek, we mailed it off. We gave Angus a different name, and we used a different e-mail address.

A month later, the results came back. They were exactly the same.

No Lab. One-eighth border collie. And no real explanation of those goofy ears.

Angus is the most affectionate dog we've ever had. He's the most obedient. He chases dried leaves when they skitter across the path, and he thinks that he can catch a bird on the wing. He plays hard with other dogs. He is healthy and strong. And he has ears that stop runners in their tracks.

Does it matter where he came from? Maybe what matters is where he is now: With us. Forever.

Laurie Hertzel is not a dog expert, just a dog lover. She is chronicling the first few months of her puppy's life on these pages.

Coming June 16: How much training is too much training? Read previous installments at startribune.com/puppy