Elena is a 25-year-old software engineer who struggles with commitment. She often worries that her partner does not truly love her and becomes highly anxious and jealous when they spend time with friends. When she was a toddler, her mother was frequently inconsistent in her caregiving, sometimes being highly attentive but often being emotionally unavailable.

Elena's colleague, Marcus, is secure, independent, and forms stable, trusting relationships; his parents were consistently warm and responsive during his infancy.

Discuss research into how early attachment style influences later childhood and adult relationships. Refer to Elena and Marcus in your answer.