Objectives: The association between body height and social status is known. We were interested in the effect of intergeneration changes in social status on height. Methods: Body height was measured in 2008 paternal grandfather-father-son and 1803 paternal grandfather-father-daughter triplets. The sample consisted of four child cohorts born in 1988, 1985, 1983, and 1980, and was measured annually from 6 to 11, 9 to 14, 11 to 16, and 14 to 18 years of age. Triplets were dichotomized according to grandfathers' occupation, into one "lower" and one "upper" grandparental class; and according to paternal education, into one "lower" and "upper" paternal class, resulting in four "family histories": two nonmobile (grandfathers and fathers stayed in the same social class), and two mobile histories (social class of fathers and grandfathers differed). Results: "Upper" class fathers are taller than "lower" class fathers. This class effect on height persists into the third generation. Upward social mobility ("lower" class fathers receive secondary or university education) results in taller stature both in the fathers and in the children. The opposite applies for downward social mobility. "Upper" class fathers with only basic or vocational education lose the social advantage and remain shorter. So do their children. Conclusions: The class effect on height tends to persist into the next generation, but depends on education. Upward social mobility measured as a "better" education, results in taller stature, up to the third generation. The study highlights the importance of education as a major regulator of body height.

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Heterosis is thought to be an important contributor to human growth and development. Marital distance (distance between parental birthplaces) is commonly considered as a factor favoring the occurrence of heterosis and can be used as a proximate measure of its level. The aim of this study is to assess the net effect of expected heterosis resulting from marital migration on the height of offspring, controlling for midparental height and socioeconomic status (SES). Height measurements on 2,675 boys and 2,603 girls ages 6 to 18 years from Ostrowiec Świętokrzyski, Poland were analyzed along with sociodemographic data from their parents. Midparental height was calculated as the average of the reported heights of the parents. Analyses revealed that marital distance, midparental height, and SES had a significant effect on height in boys and girls. The net effect of marital distance was much more marked in boys than girls, whereas other factors showed comparable effects. Marital distance appears to be an independent and important factor influencing the height of offspring. According to the "isolation by distance" hypothesis, greater distance between parental birthplaces may increase heterozygosity, potentially promoting heterosis. We propose that these conditions may result in reduced metabolic costs of growth among the heterozygous individuals.

health-related quality of life (HRQOL), quality of well-being scale (QWB), World Health Organization quality of life instruments (WHOQOL-BREF).Słowa kluczowe: jakość życia w ujęciu zdrowia (HRQOL), kwestionariusze oceny (QWB), World Health Organization quality of life instruments (WHOQOL-BREF).

Aim of the study is to assess the relationship between screen time, physical activity and physical fitness among girls 6–7 years-old. 21,528 girls aged 6 and 7 from Poland were assessed in terms of physical fitness. Arm strength, abdominal strength and explosive strength of the lower limbs were measured using the EUROFIT test. Basic somatic features were measured and BMI and WHtR indices were calculated. Spontaneous and organized physical activities as well screen time were assessed by the parents utilizing a questionnaire. The multiple logistic regression method was used to evaluate the influence of screen time and spontaneous physical activity on various components of physical fitness. Physically active (PA) girls (≥1h/day) and those who participated in additional physical activities (APA) during the week had significantly higher height, weight, and BMI (p<0.001), but not WHtR. They had a higher level of flexibility, explosive strength of the lower limbs and arm strength (p<0.001). With an increase in screen time, the BMI, WHtR increased significantly and explosive strength of the lower limbs, abdominal strength and arm strength were lower. Regression analysis showed that more frequent participation in extracurricular activities increased the values of BMI and WHtR in quartile 4 (Q4), and strength components: Q2–Q4 (p<0.05). Spontaneous physical activity was positively related to the values of BMI, WHtR (both: Q4; p<0.05), explosive force of lower limbs (Q3–Q4; p=0.001), and negatively related to arm strength (Q2; p=0.001). Screen time (≥2hrs/day) increased odds for higher BMI values (p<0.05). Each screen time category decreased the odds of achieving abdominal muscle strength related to the quartiles: Q2–Q4 (p<0.05), arm strength (Q4: p<0.05). ST (1 <2hrs/day) decreased arm strength (Q3; p= 0.045). Our research has shown that screen time-related sedentary behavior and physical activity affect overweight and obesity indices (especially BMI) and strength abilities. The observed associations more often affected girls with a higher level of fitness The results observed in girls aged 6-7 indicate a need for early intervention aimed at limiting time spent watching TV and computer use, as well as to encourage both spontaneous and organized physical activities.