The is the most accurate and commonly used technique psychologists follow to collect data

The answer to this question is the scientific method. A scientific method is a technique used in gathering new data or knowledge which ia consisting of testing, observation, measurement, and forming of hypothesis or conclusion. The scientific method is used to test hypothesis and to help scientist to solve or form a solution to the problem.

  separated twins develop traits that differ according to the environments in which they are raised.

Immunization is the introduction of a foreign substance to provoke  the immune response system.  immunizations are the same as vaccinations. it introduces foreign (but dead/ weakened) illnesses to train the body to fight against them. specific viruses and bacteria have specific antigens, antigens act sort of like name tags. these name tags the immune system recognize what's dangerous to the body and what's safe.