My parents are celebrating their 40th anniversary next month, and the occasion got me thinking about relationships and compromise. Mom is a media mogul who goes out for work functions almost as much as I do; Dad is a circuit court judge who’s asleep by eight every night. She does the cooking; he does the eating. She cleans up; he feeds the dogs. She has a standing manicure appointment every Saturday; he has a standing tee time every Sunday. Their schedule seems to work for them, despite personalities on the opposite ends of the spectrum. She’s a Type A; he’s a Type XL (as in extra laid-back). She’s a social butterfly; he has a hard time remembering all of his friends’ names.

They’re not necessarily what you’d expect from soul mates, but since getting set up at the University of Illinois in 1965, they’ve been making it work for almost 40 years. So I asked around: Is there such a thing as a soul mate, or do we mold our own perfect matches, morphing someone into Mr. or Mrs. Wonderful?

“It’s like building a house,” says 33-year-old Paul, who’s been married five years. “Unless you build it from scratch and create every detail the way you want it, you will ultimately have to make sacrifices. It’s about compromise.” He believes people can change, but only if they really want to. “You can’t change the foundation or essence of a person-you can’t transform a three-bedroom house into a six-bedroom house-but people do evolve in relationships, if they want to.”

Meghan, 33, who’s been married for seven months, believes there’s more than one soul mate out there for everyone. “My husband and I are unbelievably compatible, but I’m not sure if I would say we’re ‘soul mates.’ I think everyone has people they connect with; however, I think it can be more than one person, and I think it can be a husband or a best friend,” she says. “Relationships are based on finding someone you get along with-someone who shares the same morals and values, and whom you connect with mentally and physically. Everyone is going to change a little to mold to each other, but you cannot change a person’s core.”

Like Meghan, 34-year-old Tessa, who just celebrated four years of marriage, doesn’t believe you can shape a man, but she does think you can evolve. “Can you mold a man into the perfect mate?” she asks. “Probably not. But you can mold yourself into a tolerant, non-judgmental, and content person/mate. Then the idiosyncrasies of the man you are trying to mold won’t be as bothersome-but you’ll still get annoyed sometimes.”

Some believe the idea of a soul mate is just a myth. “I used to be a strong believer in soul mates,” says Derek, 37, who recently wed. “I think it was kind of a procrastination; I was looking for ‘the one’ rather than looking for a solid life partner. The term ‘soul mate’ is a superlative; you’re either right for each other or you’re not. It has much more to do with timing.”

OK, so soul mates may be an overly glorified, cheesy chick-flick concept, but there is something to be said for relationships that work, despite seeming less than ideal on paper. “There’s no such thing as a perfect match,” says Jackie, 33. “Everyone has her issues. To be totally cliché, my husband makes me want to be a better person. For example, when I first met him, I was a slob and-let’s say-a bit pudgy. Now I swear I have OCD when it comes to cleaning and I no longer wear a size 12. On the flip side, he was terrified to commit, and now we have a home, a kid, and are working on the happily ever after part.” Incidentally, Jackie is married to Paul; they met on July 6, 1999, married on July 6, 2002, and had their baby on July 6, 2005. Even if soul mates don’t exist, fate must.

“In reality, you are lucky if you’re good life mates or roommates, rather than ‘soul mates,'” says my oldest friend Nicole, 33, who married a man she’s known since high school; they’re approaching their 10-year anniversary. “What makes you tick on a daily basis is far from what makes the other person tick. So, after time, compromise, and often kids, you realize that if your good days and good moments outweigh the bad ones, you’re doing well.”

When I asked my parents to weigh in on soul mates, I got this response from my mom: “How could you ask this of your parents who are like night and day, and reaching 40 years?” Then she offered her secrets to a successful marriage: “Don’t sweat the small stuff. Pick your fights and let the little things go, like too many collections, messy closets and rooms, et cetera. If the basics are there, the rest will follow.” And, most importantly, she adds: “Don’t ever think you will change him. It’s not possible.”

Dad, who’s a bit more sentimental, countered: “Your mom and I are one twosome; I couldn’t exist without her. But that doesn’t mean we get along all the time or agree on things. You know each other and you accept each other; that’s being a soul mate. OK, and I wouldn’t know where my socks are without her-or what I’m doing on Saturday night.”