资料题：We can infer from the passage that pheromones are（　）。

A young girl's relationship with her family, especially with her father, may influence at what age she enters puberty (青春期), according to Vanderbilt University researchers.Girls who had close, positive relationships with their parents during the first five years of life tended o experience relatively late puberty, compared to girls who had more distant relationships with their parents.More specifically, the researchers found that the quality of fathers' involvement with daughters was the most important feature of the early family environment in relation to the timing of the daughters' puberty.Girls who enter puberty later generally had fathers who were active participants in care-giving; had fathers who were supportive t the girls' mothers; and had positive relationships with their mothers.But it's the fathers' involvement, rather than the mothers', which seems to be paramount(极为重要的)to the age of the girls' development.The researchers believe that girls have evolved to experience early socialization, with their"antennae" tuned to the fathers' role in the family (both in terms of father-daughter and father-mother relationships) and that girls may unconsciously adjust their timing of puberty based on their fathers' behavior.They present several theories as to why this occurs.One biological explanation is that girls whose fathers are not present in the home may be exposed to other adult males- stepfathers or their mother' boyfriends, and that exposure to pheromones(信 息素) produced by unrelated adult males accelerates female pubertal development.The flip side of that theory is that girls who live with their biological fathers in a positive environment are exposed to his pheromones and are inhibited from puberty, perhaps as a natural incest avoidance mechanism.Girls who live with their fathers but have a cold or distant relationship with them would notbe exposed to their fathers' pheromones as mach a girls who have more interaction with their fathers, therefore causing the girls in the distant relationship to reach puberty earlier, the researchers hypothesize(假设).Perhaps most notable, the researchers say, is the important role fathers seem to play in their daughters' development, given that the quality of mothering is generally more closely associated with how children turn ou than is the quality of fathering.