Why is it that some people seem to be ......(13)...... happier than others? An Edinburgh University study seems to know the answer. Their study of twins suggets that genes control half the .....(14)...... traits that make us happy. The other half is linked to lifestyle, career and relationships. The study looked at the results of 900 identical and non-identical pairs of twins. They measured their level of hapiness ...(15)... anxiety, sociability and conscientiousness. The results suggested that these traits were influenced up to 50% by genetic factors. Dr Alexander Weiss ....(16)..... led the research said "Together with life and liberty, the pursuit of happiness is a core human desire. Although happiness is subject to a wide range of external influences, we have found there is a component of happiness which can be entirely explaned by genes." .....(17)......, another expert said tat we can still train ourselves to be happier. "Simple things, such as keeping a journal where you write down, every night, three thing that you are grateful for have been shown to deliver improvements" Will you try it? Question 13: A. affectedly B. spontaneously C. unusually D. naturally Question 14: A. personnel B. persons C. personality D. personally Question 15: A. in terms of B. regardless of C. on account of D. because of Question 16: A. which B. whom C. whose D. who Question 17: A. Besides B. Moreover C. However D. In addition to