Norwegian researchers divided 2.3 million birth records in the country over the past few decades, as well as corresponding health data on pregnant women, and found that if a mother has symptoms of hyperemesis gravidarum during pregnancy, the daughter may also develop the symptoms later in pregnancy It is three times more than other people. Studies also show that pregnancy hyperemesis is not related to whether the fetus in the abdomen contains related genes from the husband's side, and the gene that causes this symptom may only come from the mother. Therefore, researchers believe that pregnancy hyperemesis is related to father Genes are unrelated, but passed from mother to daughter. Which of the following, if true, would most weaken the above conclusion? ['The natural and domestic environment (climate, eating habits, etc. ) of the daughter and mother are similar.', 'An Asian study shows that mothers have hyperemesis gravidarum and daughters are 1.5 times more likely than others.', 'Studies show that grandma has vomiting during pregnancy, and granddaughter is three times more likely than others.', 'Over the past few decades, the proportion of Norwegian women smoking has increased year by year, and smoking has been linked to hyperemesis gravidarum.']