Do Your Genes Shape Your Outlook on Life?

You’ve probably noticed how some people in your life seem naturally upbeat and optimistic, while others focus on everything that could go wrong. Is it just easier for some people to be positive? Did others choose pessimism? And most importantly—could they change?

Then I came across fascinating research on twins that shed light on these questions. Scientists studied both fraternal twins (who share about half of their DNA) and identical twins (who share the exact same DNA). The results were eye-opening: identical twins showed strikingly similar levels of positivity, even if they were separated at birth and raised in very different circumstances. This was not the case for fraternal twins.

After hundreds of studies, researchers concluded that about 50% of our tendency to “see the glass as half full” comes from our genetics.

Why This Matters

This insight can change the way we see ourselves and others. It means the perspectives of our coworkers, friends, and family are not just about “choosing” optimism or pessimism. Their wiring—how they naturally interpret challenges, setbacks, and opportunities—plays a big role.

When I learned this, I realized I could let go of some of the judgment I carried toward people who seemed overly negative. Instead of frustration, I could offer patience and acceptance. After all, their brains might simply be wired differently than mine.

The Other 50%

But here’s the encouraging part: scientists also discovered that about 40% of our positivity is shaped by how we think. That means we can train our minds to focus differently, build habits that lift our mood, and intentionally choose practices—like gratitude or reframing—that change how we experience life.

Surprisingly, only 10% of our positivity is influenced by our circumstances—things like income, health, or where we live. Most of us overestimate the impact of these factors and underestimate the power of our mindset.

How might knowing about this research shift the way you see people in your life?

To browse (and share!) past positivity tips, visit this page.

Tina Hallis, Ph.D., is a thought-shifter! She is a professional speaker and founder of The Positive Edge, a company dedicated to helping individuals and organizations increase their positivity to improve the quality of people’s work lives and the quality of company cultures.