Interface

Unlike inheritance, which defines who you are,
an interface is what you can do — how you interact.

In high-level programming, an interface is a contract:
a class may implement it without altering its nature.

public interface IWorker { void Work(); }
public interface IPartner { void Love(); }
public interface ICreator { void Create(); }

public class Adult : Human, IWorker, IPartner
{
    public override void Evolve()
    {
        Console.WriteLine("Integrating self into system. Negotiating meaning.");
    }

    public void Work() => Console.WriteLine("Creating value within external frameworks.");
    public void Love() => Console.WriteLine("Bonding and sharing with chosen other.");
}