Fifteen evidence-led investigations of depression, behavior and mental wellbeing through twin research.
This content is general research information and does not replace medical advice, diagnosis, or individual treatment.
Brain, Mood & Behavior
All 15 articles
Article 1 of 15·7 min read
Dopamine: How Much Is Determined by Your Genes? What Twin Studies Reveal
Twin PET studies show a genetic contribution to dopamine function — but especially in reward-related brain regions, individual experience still appears to matter.
Runner’s High: Is It Really the Endorphins — Or the Body’s Own Cannabinoid System?
The classic endorphin story is only part of the picture. Human experiments now make endocannabinoids strong candidates for the euphoria and reduced anxiety some runners feel.
Can Other People’s “Energy” Affect You? What Twin Research Actually Says
If “energy” means feeling calmer, brighter, stressed or drained around certain people, science has several plausible mechanisms: emotional contagion, environmental sensitivity and physiological synchrony.
Can Sleep Problems Come Before Depression? Twin Studies Reveal a Complicated Pattern
In child twins, sleep problems came first in one longitudinal model. Adult and adolescent twin studies show why the relationship is still far from one-way.
Can Diet Affect Depression? Twin Research Gives a More Complicated Answer
Eating behaviour, medication, genetics and mental health overlap. The strongest evidence does not support a simple “eat this, prevent depression” story.
Stress Resilience: Why Can Genetically Similar People Respond So Differently?
Twin studies show that inherited differences matter — but “resilience” is not one fixed trait, and individual experiences can leave lasting differences even between genetically identical people.
ADHD Is Highly Heritable — So Why Can Identical Twins Still Differ?
High heritability does not mean genetic certainty. Twin studies show strong inherited influence alongside within-pair differences, development, measurement effects and nonshared experience.
Anxiety Can Run in Families — But Why Does It Change Over Time?
Longitudinal twin studies show that inherited influences can help explain continuity while individual-specific environmental influences often contribute to change — but the balance depends on age, phenotype and model.
Does Screen Time Really Cause Depression? What 21,797 Swedish Twins Reveal
A large Swedish twin study linked recreational screen use with later mental-health problems—but the associations weakened markedly when twins were compared within the same family.
Can Social Support Explain the Link Between Personality and Depression? What Swedish Twins Reveal
A 23-year Swedish twin study explored assertiveness, hostility, friend support and depressive symptoms—but extensive missing data limit the conclusions.
